After Windows 8 re-installation , folder became encrypted

Dear Sir,
We had a laptop installed with Windows-8 on partition c . Due to some issues , We were required to re-install the Windows-8 . Before the re-installation , We had copied a folder from c partition to d partition and then proceeded for re-installation .
We are now finding that the copied folder on partition D has become encrypted and files in this folder can't be seen .

I request members to kindly guide us as what steps need to be followed so that files gets available .

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Had to read this twice before getting to understand what is happening....
From my point of view the old install Windows had a mechanism activated called EFS (NTFS encryption) and the user had encrypted the folder you moved.

You could move the folder and see its contents because then you were holding the certificate in your certificate store.
Since you reinstalled the OS you have deleted the certificate store, so unless you have the private key backedupped somewhere OR youhave no valid backup of the previous install you have to consider that directory and its files as lost in space.

Hope you have the private key stored somewhere or have a valid backup....